Linear derailleur mechanism

ABSTRACT

A derailleur system is provided that moves the derailleur cage in a substantially rectilinear path. The derailleur is mounted to a frame having a gear cassette mounted thereon. The gear cassette includes an axis of rotation. The derailleur includes a drive member engaging the gear cassette. The derailleur is positioned on the frame adjacent the gear cassette, and including a spatial linkage having a stationary link, a floating link, and a cage assembly having two pulleys each defining an axis of rotation. The drive member engages each of the pulleys. The path of the floating link is substantially linear through substantially its entire range of motion and variously aligns at least one of the pulleys with the gear cassette.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/090,220 filed on, Dec. 10, 2014 entitled “Linear DerailleurMechanism,” the content of which is hereby incorporated by reference inits entirety.

TECHNICAL FIELD

Discussed herein is a bicycle derailleur and, with more particularity, aderailleur at operates in a linear motion shifting the bicycle drivebetween cassette cogs.

BACKGROUND

Bicycles are commonly provided with a series of parallel cogs/sprocketsof varying diameter/tooth-counts fixed to the rear wheel of the bicycleconcentric to the wheel axis, also considered a rear gear cassette. Thecogs are typically arranged in a cone-like shape from small gear tolarge gear. A bicycle rider transfers power via the cranks (having acrank axis) in which a front chain ring is fixed. The front chain ringmay include more than one cog/sprocket having differing sizes (e.g. alsoforming a cone) and be considered a front gear cassette. A drivechain/belt travels over the chain/belt ring to one of the rear cogs in aclosed loop, driving the rear wheel.

The gear ratio between the front chain ring (power input) and rear wheel(power output) is determined by which rear cog the drive chain/belt hasengaged. An example of a prior art rear derailleur used to shift thechain/belt is disclosed in FIG. 1. The rear derailleur 10 is a linkagemechanism that controls the position of the drive chain/belt 5 relativeto individual cogs/sprockets 6 of the rear wheel. Currently, a linkageused in a rear derailleur 10 such as those commonly used today is a2-dimensional planar 4-bar linkage 11 having a parallelogram structure.The resultant path of the floating link 20 of this mechanism isnon-linear, forming a curved or arcuate path. As a result, the angle ofthe derailleur pulley axes 17, 19 are not constant relative to the wheelaxis 7 in at least one reference plane throughout the entire travelrange, which can create undesirable forces and negatively affectperformance and wear and tear on the components. The wheel axis 7 is theaxis defined by the rotation of the wheel hub 2.

Typical rear derailleurs 10 have of a parallelogram linkage 11 as shownin FIG. 1. One link, the stationary link 14, is fixed or pivotallymounted at connection 12 to the rear derailleur hanger 3 of the bicyclerear triangle 1 or swingarm, or to the rear triangle/swingarm itself.Two parallel links 16, 18 connect the floating link 20 to the stationarylink 14. An actuation force is applied to change the position of themechanism, typically via a cable. A return spring is connected to theparallelogram providing a force opposite to that of the actuation force.A derailleur cage assembly 30 is pivotably connected to the floatinglink 20. The derailleur cage assembly includes an upper pulley or jockeypulley 31, and a lower pulley or idler pulley 32.

Currently the most common linkage design used in rear derailleurs todayis a planar 4-bar linkage parallelogram. There are several disadvantagesto this mechanism. For example, the resultant path this linkage definesis non-linear curved. As a result, the angular relationship of thederailleur pulley axes 17, 19 varies with respect to the wheel axis 7throughout the range of motion. The inherent geometry of theparallelogram leaves little freedom of the linkage mounting locationrelative to the rear wheel to achieve the desired linkage path. Thislimited freedom correspondingly limits frame designers options, whereasmore freedom of this mounting location would give frame designer moreoptions.

As noted previously, derailleur linkages 11 are activated via anactuation force to move the mechanism through its travel. Moving themechanism through its travel causes the chain 5 to shift from one wheelcog in the cassette 6 to another wheel cog. One end of the actuationcable is connected to one of the non-stationary links 20 and the otherto the stationary link 14 or bike frame itself. With a parallelogramdesign, the mechanism's linkage path is dependent upon the link lengthsand axes geometry. In order to achieve an optimum linkage path andactuation ratio in a parallelogram mechanism, it is common to addadditional complex features such as pulley wheels and extended links.These items add weight and complexity.

The inherent geometry of the parallelogram leaves little freedom tominimize the mechanism's volume envelope and envelope position relativeto the drive side frame dropout. It is desirable to have a compactmechanism located as inboard as possible to the frame to minimize thechance of hitting the derailleur on an obstacle while riding, which canprove difficult to achieve with this design.

A mechanism that offers various solutions to the inherent mechanicallimitations of a parallelogram design discussed above is desired.

SUMMARY

In accordance with various embodiments, a bicycle may include a framehaving a gear cassette mounted thereon, the gear cassette having an axisof rotation, and a drive member engaging the gear cassette. The bicyclemay also include a derailleur positioned on the frame adjacent the gearcassette, and including a linear linkage The linear linkage may includea stationary link and a floating link. The derailleur may include a cageassembly having two pulleys each defining an axis of rotation. The drivemember may engage each of the pulleys. The path of the floating link maybe substantially linear through substantially all of its range ofmotion.

In accordance with various embodiments, the gear cassette may be a reargear cassette operably associated with a rear wheel. The gear cassetteis a front chain ring set operably associated with a crank. The pulleyaxes of the cage assembly may be parallel to the axis of rotation of thegear cassette and remains parallel to the axis of rotation of the gearcassette throughout its entire range of motion. The pulley axes of thecage assembly is not parallel to the axis of rotation of the gearcassette and remains not parallel to the axis of rotation of the gearcassette throughout its entire range of motion. The spatial link may bean over-constrained spatial 6R linkage. The fixed link may be attachedto the bicycle frame. The cage assembly may be pivotally connectedconcentrically on the floating link. The cage assembly may be pivotallyconnected eccentrically on the floating link.

In accordance with various embodiments, an actuation force may beapplied to the derailleur to cause motion from a first position to asecond position. At least one return mechanism may be utilized to urgethe derailleur from the second position towards the first position. Theactuation force may be a mechanically, electrically, or hydraulicallydriven. The return mechanism may include at least one spring selectedfrom one of the group of a torsion spring, and/or an extension spring.The input activation of the linkage may be via a mechanical cable. Theinput activation of the linkage may be via an electronic servo. Theinput activation of the linkage may be via a hydraulic plunger.

In accordance with various embodiments, a derailleur for a bicycle mayinclude a frame having a gear cassette mounted thereon. The derailleurmay also include a stationary link and a floating link. The path of thefloating link may be substantially linear through substantially all ofthe floating link's range of motion. The floating link may be operableto move a drive member. The drive member may be operable to engage agear cassette. The stationary link may be operable to be biased to besubstantially stationary relative to a frame having the gear cassettemounted thereon. The gear cassette may have an axis of rotation. Thestationary link may be positioned on the frame adjacent the gearcassette.

In accordance with various embodiments, the gear cassette is a rear gearcassette operably associated with a rear wheel. Alternatively, the gearcassette may be a front gear cassette operably associated with a crank.The pulley axes of the cage assembly may remain parallel to the axis ofrotation of the gear cassette throughout its entire range of motion. Thelinear derailleur may include a spatial link that is an over-constrainedspatial 6R linkage. The Stationary link may be positioned relative toand attached directly or indirectly to the bicycle frame. The cageassembly may be pivotally connected concentrically on the floating link.The cage assembly may be pivotally connected eccentrically on thefloating link. An actuation force may be applied to the derailleur tocause motion from a first position to a second position, and at leastone return mechanism may be utilized to urge the derailleur from thesecond position towards the first position. The actuation force may be amechanically, electrically, or hydraulically driven. The returnmechanism may include at least one spring selected from one of the groupof a torsion spring, and/or an extension spring. The input activation ofthe linkage may be via a mechanical cable. The input activation of thelinkage may be via an electronic servo. The input activation of thelinkage may be via a hydraulic plunger.

In accordance with various embodiments, a bicycle may include a framehaving a gear cassette mounted thereon, the gear cassette having an axisof rotation, and a drive member engaging the gear cassette. The bicyclemay also include a derailleur positioned on the frame adjacent the gearcassette. The derailleur may have a stationary link and a floating link.The path of the floating link may be substantially linear throughsubstantially its entire range of motion. The stationary link may beconnected to the floating link via a fist linkset and a second linkset.Each linkset may have a plurality of axes of rotation. The axes ofrotation in the first link set are not parallel to the axes of ration inthe second linkset

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a typical embodiment of a prior art rear derailleurfor a bicycle;

FIG. 2 illustrates an isometric view of a rear wheel of a bicycle havinga derailleur;

FIG. 3A illustrates an isometric rear view of a linear derailleur inaccordance with an exemplary embodiment;

FIG. 3B illustrates an isometric side view of a retracted linearderailleur of FIG. 3A in accordance with an exemplary embodiment;

FIG. 3C illustrates an isometric side view of an extended linearderailleur of FIG. 3A in accordance with an exemplary embodiment;

FIG. 3D illustrates a isometric rear view of the derailleur of FIG. 3Ain accordance with an exemplary embodiment;

FIG. 4A illustrates an exploded view of an exemplary linkage of a linearderailleur;

FIG. 4B illustrates an isometric view of a plurality of differentpositions along a linear path;

FIG. 4C illustrates an isometric view of an example linkage withlinksets having different axes of rotation;

FIG. 4D illustrates an isometric view of a counter example linkage withlinksets having parallel axes of rotation;

FIG. 4E illustrates an isometric view of an example linkage with a crossconfiguration;

FIG. 4F illustrates an alternate isometric view of an example linkagewith a cross configuration;

FIG. 4G illustrates an isometric view of an example linkage with an openconfiguration;

FIG. 4H illustrates an alternate isometric view of an example linkagewith an open configuration;

FIG. 5A illustrates a side view of a linear derailleur in accordancewith an exemplary embodiment;

FIG. 5B illustrates a rear view of a linear derailleur in accordancewith an exemplary embodiment;

FIG. 5C illustrates a top view of a linear derailleur in accordance withan exemplary embodiment;

FIG. 5D illustrates a side isometric view of a linear derailleur inaccordance with an exemplary embodiment;

FIG. 5E-F illustrate a rear view of extended and contracted linearderailleurs in accordance with an exemplary embodiment;

FIG. 6A-B illustrate a side view of a concentric linear derailleur inaccordance with an exemplary embodiment;

FIG. 7A-B illustrate a side view of an eccentric linear derailleur inaccordance with an exemplary embodiment;

FIG. 8 illustrates an isometric rear view of a linear derailleur inaccordance with an exemplary embodiment;

FIG. 9A-B illustrate rear and top isometric views of a linear derailleurin accordance with an exemplary embodiment;

FIG. 10 is a graph comparing the horizontal derailleur movement ofvarious derailleurs with the resultant angles of the pulley axes as theyaw and roll;

FIG. 11 is a graph comparing the horizontal derailleur movement ofvarious derailleurs with the resultant angles of the pitch of the pulleyaxes;

FIG. 12 is a graph comparing the horizontal derailleur movement ofvarious derailleurs with the resultant angles of the pulley axes as theyaw and roll;

FIG. 13 is a graph comparing the horizontal derailleur movement ofvarious derailleurs with the resultant angles of the pitch of the pulleyaxes; and

FIG. 14 is a graph comparing the derailleur movement with the actuationmovement.

DETAILED DESCRIPTION

The present disclosure is related to a derailleur mechanism for abicycle used to change the position of the drive chain relative toindividual cogs/sprockets on the bicycle drive train. In one example,the cogs/sprockets are a part of the rear dive mechanism on the rearwheel. The drive chain is moved via a remote control known as a shifter.A change in the active rear wheel drive cog changes the gear ratiobetween the front chain-ring (power input) and rear wheel (poweroutput).

The present disclosure differs from traditional derailleurs in that thederailleur pulley axes remain substantially constant relative to thewheel axis throughout the entire travel range. This particular relativemovement is achieved by providing a derailleur with a linear linkagemechanism. As an example, the linear derailleur includes anover-constrained 6R spatial linkage (e.g. a Sarrus linkage) which iscapable of substantially linear motion of the floating link. As aresult, the angles of the pulley axes and the wheel or crank axis remainconstant relative to one another. This linear motion allows for eitherof a concentric or eccentric mounting of the derailleur cage on thelinkage system.

Despite being discussed in the embodiment of a rear derailleur herein, aperson of ordinary skill in the art will appreciate that the conceptsand elements of the linear derailleur 100 can also be adapted to beutilized as a front derailleur on a bicycle in addition to or in thealternative of a rear derailleur. However, as an example to be discussedin more detail herein and as shown in FIG. 2, the linear derailleur 100may hang from the rear triangle 1 of a bicycle in order to shift thedrive mechanism 5 (e.g. chain belt or the like) between the rear cogs ona cassette 6. As a matter of orientation and as shown in FIG. 2, theforward direction may be in the X direction, the upward direction may bein the Y direction, and the front side direction may be in the Zdirection, which is shown at the rear wheel rotation axis.

In accordance with various embodiments, a bicycle includes a linearderailleur 100. For example, the linear derailleur is a rear derailleur100. As illustrated by way of example in FIG. 3A, the linear derailleur100 includes a hanger 3 which hangs from the rear triangle 1 (not shown)to suspend the derailleur 100 from the bicycle.

In the various embodiments, the linear derailleur 100 includes a movableconnection 110. The movable connection 110 is formed of a mechanismoperable to drive at least a portion of the cage assembly 30 in a linearpath. In one example, the movable connection 110 includes a stationarylink 140 that is connected relative to a bike frame, e.g. via the hanger3 or in some embodiments directly connected to the bike frame 1. In oneexample, the stationary link 140 is substantially fixed relative to thebike frame. While the term fixed is used herein, it should beappreciated that, the stationary link 140 may have one or more degreesof freedom such as being rotatable relative to the bike frame. Thisfreedom may be substantially limited via use of biasing springs. Thedegrees of freedom may also or alternatively be restrained via afastener or similar means such that the stationary link 140 maintains asubstantially consistent position relative to the bike frame afterassembly. The stationary link 140 may be adjustable via a torsion screwthat is operable to make minor adjustments to better calibrate thestationary link and the derailleur in general relative to the cassette.A person of ordinary skill in the art will appreciate typical methodsfrom mountain a stationary link 140 based on understanding of the artand disclosure provided herein.

In various examples, the movable connection 110 includes a floating link150 that is movably connected to the stationary link 140. The floatinglink 150 moves in a substantially rectilinear relationship to thestationary link 140. As such, the floating link 150 is substantiallyconstrained to a single rectilinear degree of freedom. While particularmechanisms that connect the floating link 150 to the stationary link 140are discussed herein in greater detail, it should be appreciated by aperson of ordinary skill in the art that other rectilinear connectionsmay be incorporated as well. For example, the floating link 150 to thestationary link 140 can be connected via a linear rail mechanism orother linear mechanisms suitable to maintain the rectilinear degree ofmovement between the floating link 150 and the stationary link 140.

The stationary link 140 includes a frame connection operable to keep thestationary link 140 positioned relative to the frame as discussed above.In one example, the stationary link 140 is contiguously formed with theframe. In another example, the stationary link 140 is removablyconnected directly to the frame. In another example, the stationary link140 is connected to a frame bracket (e.g. a derailleur hanger 3).

In accordance with various embodiments, the derailleur 100 includes anactuator 170 that is operable to move the stationary link 140 and thefloating link 150 relative to one another. The stationary link 140 mayhave a bracket 162 operable to retain, contact, or mount an actuator toform an actuator mounting feature. In one example, as shown in FIGS.3A-C, the stationary link may have a bracket 162 suitable for retainingcable 170 forming a cable bracket. In the example, the cable bracket 162is operable to house the cable and/or mount a cable adjustment barrel tothe stationary link 140. However, other actuator setups are alsoenvisioned herein as discussed herein with regards to FIGS. 8-9, whichvariously show setups including a piston/linear servo set up and arotary servo set up variously mounted to the stationary link 140.

In accordance with various embodiments, the derailleur 100 includes abiasing mechanism 132 that is operable to return the stationary link 140and the floating link 150 to an unactuated position in the absence of anopposing force from actuator 170. The stationary link 140 may also havea mount 130 for a biasing mechanism 132. A biasing mechanism may beoperable to return the derailleur system to a compressed, extended, orintermediate state absent force from the actuator. As an example, mount130 may retain an extension spring on the stationary link 140. A secondmount 134 may be positioned on the movable connection 110 and operableto retain the opposite end of the biasing mechanism 132. Othermechanisms may be used in addition to or as alternatives to theextension spring. For example, as shown in FIG. 3D one or more torsionsprings 155 may be attached between the various links (e.g. a first link152 and the stationary link 140 discussed in more detail herein) to biasthe floating link 150 toward an unactuated position such as thecollapsed configuration shown. As such, a derailleur cage assembly 30that includes of an upper pulley or jockey pulley 31, and a lower pulleyor idler pulley 32 is pivotably attached to the floating link 150. Oneor more return springs 132 or 155 can be used to provide a forceopposite to that of the actuation force. By way of example, thesebiasing mechanisms 132 can be torsion springs 155 located at one or moreof the linkage pivots, or one or more extension springs 132 connected totwo points in the mechanism. However, it is appreciated that otherbiasing mechanism may be used as well.

In accordance with various embodiments, the derailleur 100 includes acage assembly 30 comprising jockey and idler pulleys. In variousexamples, the floating link 150 includes a cage hanger portion 151operable to keep the floating link 150 positioned relative to thederailleur cage 130. The floating link 150 may be contiguously formedwith the derailleur cage 30, connected directly to the derailleur cage30, or connected to a bracket extending from the derailleur cage 30. Inthis way, at least a portion of the derailleur cage 30 moves in the samerectilinear motion as the floating link 150. This movement may allow thederailleur cage 30 to align with the cassette 6 such that the chain/belt5 can move between separate gear rings. The mount between the floatinglink 150 and the derailleur cage 30 may be concentric with the jockeypulley or it may be eccentric with the jockey pulley.

In accordance with various embodiments, the movable connection 110 maybe formed via one or more link sets. For example, the connection 110includes a first link set 145 a and a second link set 145 b. The firstlink set 145 a includes a first link 152 and a second link 154 that arerotatably connected to each other at a hinge 156. The second link setincludes a third link 142 and a fourth link 144 that are rotatablyconnected to each other at a hinge 148. One or more of the links such aslink 152, as shown in the FIGS. 3A-C, may include a link extension 153that is connected to an actuator 170 (e.g. actuation cable or piston).From this position, the actuator 170 can contract the link extension 153toward the actuator mount 162. This action causes the floating link 150to extend away from the stationary link 140 in a rectilinear path. Inother embodiments, a servo may rotate link 152 with respect to thestationary link 140 similarly causing the floating link to extend awayfrom the stationary link.

Each of the first link set 145 a and the second link set 145 b arerotatably connected to each of the stationary link 140 and the floatinglink 150 via hinges 146, 149, 158, and 159. For example, the stationarylink 140 may include the first hinge joint 146 and the second hingejoint 149 operable to connect to links 152 and 142, respectively. Thefloating link 150 may include the third hinge joint 158 and a fourthhinge joint 159 as shown in FIG. 3B. The joints 158, 159 are operable toconnect the floating links to links 154 and 144, respectively.

In accordance with various embodiments and as discussed above, themovable connection 110 is a linkage that provides a single degree offreedom in a rectilinear motion. For example, the movable connection 110is an over-constrained 6R spatial linkage (such as e.g. a Sarruslinkage) which is capable of providing substantially rectilinear motionbetween the stationary link 140 and the floating link 150. Such astructure allows the derailleur 100 to have a substantially rectilinearmotion created by the over-constrained 6R spatial linkage (such as aSarrus linkage). This structure overcomes the non-linearity issuesassociated with a typical derailleur structure. Furthermore, thisderailleur structure also may allow a smaller package to reduceinterference with other components or ground effects during riding. TheSarrus linkage is an example of a 6R spatial mechanism. A 6R spatialmechanism is one that includes 6 links with revolute joints and at leastone link axis is not parallel to another within the system. Accordingly,the Sarrus linkage is significantly different than the traditionalparallelogram linkage typically used in derailleurs today.

In accordance with various embodiments, each of the hinges of themovable connection 110 has an axis. At least one of the axes through thehinge joints of the movable connection 110 forms an angle other than 0degrees or 180 degrees with respect to at least one other axis. The twoaxes may, however, be planar or skew with respect to each other. Invarious embodiments, each of the hinge axes associated with the firstlink set 145 a are parallel and each of the hinge axes associated withthe second link set 145 b are parallel. However, in this embodiment, thehinge axes of the first link set 145 a and the hinge axes of the secondlink set 145 b are not parallel.

The following information related to an over-constrained mechanicalsystem is provided below to provide a broader understanding of theapplicability, structure and theory of the system without any intentionon being bound by the theory provided herein. As indicated above, a 6Rspatial linkage, such as a Sarrus linkage, may be incorporated into aderailleur system, which may be used in the various structure providedherein. Such a linkage may include two special properties: 1) It is anover-constrained mechanism; and 2) The linkage is capable of rectilinearmotion.

To touch on the theory underlying various linkages, the followinganalysis known as the Mobility Analysis of Mechanisms (Kutzbach (orGrübler) mobility criterion) can be used to describe the mobility of alinkage. The mobility m of a linkage composed of n links that areconnected with p joints:

mobility=m=6(n−p−1)+Σf

n=number of links

p=number of joints

Σf=sum of the kinetic variables in the mechanism

Revolute joints or rotary hinges allow one degree of freedom movementbetween the two links they connect. For an n-link closed loop linkagewith revolute joints:

Σf=n

p=n

m=6n−6p−6+n

m=6n−6n−6+n

m=n−6

So in general, to obtain a mobility of one a linkage with revolutejoints needs at least seven links. However, it was found that thiscriterion is not always a necessary condition to achieve mobility. It ispossible for there to be a specific geometric condition of a linkageallowing mobility even though it does not obey the mobility criterion.This type of mechanism is called an over-constrained mechanism. In thecase of a Sarrus linkage:

m=6−6=0

However, the Sarrus Linkage has m=1which makes it over-constrained.

As illustrated in the schematic diagram of the linkage system providedin FIGS. 4A-D, an over-constrained 6R spatial linkage and its linksinclude a stationary link 140 corresponding to the fixed side of thelinkage and a set of non-stationary links The non-stationary linksinclude floating link 150, linkset 145 a, and linkset 145 b. The linkset145 a may include links 142 and 144. The linkset 145 b may include links152 and 154. As illustrated in this example, all three axes N, P, and Rof linkset 145 a are parallel. Additionally, as illustrated in thisexample, all three axes M, Q, and S of linkset 145 b are parallel.

In accordance with various embodiments, each of a pair of end links(e.g. the stationary link 140 and the floating link 150) can include tworotatable connection portions such as connectors 141 a, 141 b or 151 a,151 b. Each mid link such as linkset 154 a and 145 b includes rotatableconnection portions (e.g. 155 a, 157 b, 143 a, or 147 b) that areoperable to engage with the connectors of the end links The connectionsmay be made via the matching of the rotatable axes of each componentpiece as shown for example in FIG. 4A. For example, M of link 140 with Mof link 152, S of link 154 with S of link 150, R of link 150 with R oflink 147 b, and N of link 142 with N of link 140. This assembly allowsfor the linear actuation of an example of the motion mechanism 110 in alinear derailleur 100. As shown in FIG. 4B, the rectilinear path offloating link 140 relative to stationary link 150 basses through theadjacent linear positioned denoted by A, B, and C in the figure. A is acollapsed position. B is an intermediate linear position. C is anexpanded linear position.

Again not to be bound by theory but to provide a broader disclosure, itis understood theoretically that in order for the spatial linkage toconstrain the floating link 150 to a rectilinear path, certainconditions should be met. In one embodiment, with a 6R linkage, Rdenoting revolute joints or rotary hinges that allow one degree offreedom movement between links (see e.g. FIG. 4A), all three pivot axesof the first linkset 145 a are be parallel to each other, all threepivot axes of the second linkset 145 b are parallel to each other, andthe first linkset's pivot axes N, P, and R are not parallel to thesecond linkset's 145 b pivot axes M, Q, and S. Such a system isillustrated in FIG. 4C. The floating link is constrained to arectilinear path and may be suitable for use in one or more of thevarious linear derailleur embodiments as described in this disclosure.

The structure provided herein allows for great flexibility to tune themechanism to have the desired design goals since many variables can bemodified. For example, the linksets can be configured in a crossedconfiguration as illustrated in FIGS. 4E and 4F. Or in another example,the linksets can be configured in an open configuration as illustratedin FIGS. 4G and 4H.

The mounting positions on the stationary and floating links can vary aswell. For example, the floating link 150 can have longer or shorterconnection portions 151 a, 151 b. In another example, the stationarylink 140 can have longer or shorter connection portions 141 a, 141 b.Additionally or alternatively, the pivot axes can be rotated.Additonally, the mechanism can be rotated and still achieve the samelinear motion. In the various embodiments, the lengths of links 142,144, 152 and 154 can vary independently of the mechanism's 110 linearmotion. With rectilinear actuation, the mechanism 110 can be rotated inany direction and the travel of the floating link 150 is the same linearpath. In a structure that holds the bottom link portion stationary (e.g.stationary relative to the bike frame), the upper floating link moveslinearly along the path A, B, and C shown in FIG. 4B. With the mechanismrotated 90 degrees and the lower link stationary, the upper link stillmoves in the same linear fashion in the exact same path. This is incontrast to the traditional parallelogram linkage, which would have anoutput motion that is curvilinear. That curvilinear path would alsorotate 90 degrees, creating a new orientation in contrast to themechanism illustrated in FIGS. 4A-H. By maintaining the same pathindependent of the lower/upper link rotation orientation, there is a lotof flexibility in setting the linkage orientation while achieving thesame or substantially similar resultant path of travel.

Modifying the adjustable variables affects many attributes of thelinkage but do not necessarily affect the linear path. A few examples ofthe attributes that may be affected by the adjustable variables includestiffness, travel range, packaging, mechanism envelope, actuation ratiorelative to motion, and actuation point.

With regards to stiffness, the lateral stiffness of the mechanism 110changes depending on the linkset angles and individual link lengths.This stiffness change is in addition to the link depth and width, thematerial, and the pivot construction, e.g. bearing/bushing and axletype/size. For instance, the closer 145 a and 145 b are toperpendicular, the stiffer the linkage generally is. So althoughtheoretically the linksets' 145 a and 145 b axes are operable to achievelinear motion of the floating link with the axes slightly out ofparallel, in practicality this would be difficult to achieve due to flexin individual links and revolute joint tolerances. As such, as anglesbetween the linksets' respective axes angles approach perpendicular, thestiffness is increased. With regards to travel range, the longer thelinks 142, 144, 152 and 154, typically the longer the travel range. Assuch, by maximizing the length of the links 142, 144, 152 and 154relative to the desired package size, the travel of the derailleur ismaximized.

With regards to packaging, meaning the location of the derailleur'sfixed side mounting, the fixed link can be located in many locations in3d space to achieve the same linear path. The linear derailleur is notsensitive to the orientation of the stationary link 140's positionbecause the movement is rectilinear from that location, whereas systemswith a curvilinear path are sensitive to the orientation of thestationary link. With regards to the mechanism envelope, the linkset'slocation and orientation can be configured to minimize the mechanismenvelope. For example and as illustrated in FIG. 4E-4F, the linkset 145a and the linkset 145 b can be placed into a crossed pattern so that thelinksets 145 a and 145 b fold in on themselves to save space. The crosspattern is also helpful to prevent interference between the links duringthe travel range. Alternatively as illustrated in FIG. 4G-4H, thelinkset 145 a and the linkset 145 b can be placed into an openconfiguration. An open configuration provides additional packaging roombetween the station link 140 and the floating link 150 that could beoccupied by additional derailleur features.

With regards to actuation ratio relative to motion, the actuation ratiocan be changed simply by modifying individual link 142, 144, 152 and 154lengths. This can be done with little to no effect on the constrainedlinear motion of the mechanism. With regards to actuation point, anynon-stationary link can be used to activate the motion of mechanism 110motion. Utilizing any non-stationary link provides options in designsince the envelope and packaging of various alternative portions of thederailleur can be utilized with the linear derailleur. Thus, more designfreedom is allowed.

Referring back to FIG. 2, a global coordinate system relative to abicycle is provided. The origin is coincident to the rear axle axis andthe centerline of the bike. X-positive is the direction the bicycletravels straight forward. Y-positive is upwards direction perpendicularto the ground. Z-positive is collinear to the wheel axis pointingtowards the drive-side of the bicycle. Therefore, the cassette sprocketsand front chain-ring(s) are parallel to the XY plane. Furthermore, theglobal axes of rotation of this coordinate system are also defined. X isthe roll axis, Y is the yaw axis, and Z is the pitch axis. The standardright-hand rule denotes polarity.

In the traditional linkage design used in rear derailleurs, e.g. aplanar 4-bar linkage forming a parallelogram, the resultant path definedis non-linear or curvilinear. The axes of the parallelogram are notparallel to the wheel axis. As a result, the upper and lower pulley axesdo not remain parallel to the wheel axis throughout the entire range ofmotion. In contrast, the linear derailleur, such as one with a spatiallinkage, constrains the path of the rear derailleur floating link 150 toa substantially rectilinear motion. This is unique in that the spatiallinkage constrains the floating link 150 to a substantially rectilinearpath as opposed to a non-linear or curvilinear path. The rectilinearpath that the floating link 150 and, therefore, the derailleur cage 30takes can be, but does not have to be, parallel to the XY, YZ, or XZplanes. Depending on the design intent, the linear path can be locatedanywhere in 3d space near the rear wheel cogs.

As illustrated in FIGS. 5A-D, an example linear Path is shown in the XYplane (FIG. 5A), YZ plane (FIG. 5B), XZ plane (FIG. 5C), and isometricview FIG. 5D. The path in each of these views forms a rectilinear pathextending from the top right of each figure to the bottom left. Thefloating link 150 and some portion of cage 30 follows these paths intheir respective rectilinear motion. By moving the cage 30 in such aconsistent manner, overall shifting and functionality of the derailleuris improved over traditional types.

The system discussed herein may be influenced by the angularrelationship between the derailleur pulley axes and the wheel axisthroughout the travel range of the mechanism. With the global coordinatesystem defined the yaw angle, the roll angle, and the pitch angle can bediscussed to define the rotation of the pulley axes in three dimensionalspace. With regards to the yaw angle, the yaw angle is the rotation ofthe pulley wheel axes about the global yaw axis Y. It is the angularvalue of one of the pulley axes projected onto the XZ plane measuredrelative to the Z axis. With regards to the roll angle, the roll angleis the rotation of the pulley wheel axes about the global roll axis X.It is the angular value of one of the pulley axes projected onto the YZplane measured relative to the Z axis. With regard to the pitch angle,the pitch angle is the rotation of the pulley wheel axes about theglobal pitch axis Z. It is the angular value of one of the pulley axesprojected onto the XY plane measured relative to the Y axis.

As discussed herein and illustrated in FIGS. 6A and 6B, the derailleurcage assembly 30 includes an upper pulley or jockey pulley 31, and alower pulley or idler pulley 32. The derailleur cage assembly 30 ispivotally mounted to the floating link 150. There are many possibleconfigurations of pivotally attaching the derailleur cage assembly 30 tothe floating link 150. The different configurations affect the motion ofthe jockey 31 and idler pulley 32 throughout the travel of thederailleur 100. In one example and as illustrated in FIGS. 6A-B, thecage assembly 30 can be mounted on the floating link 150 with the jockeypulley 31 positioned concentrically relative to the pivotal attachment182. In a second example and as illustrated in FIGS. 7A-B, the cageassembly 30 can be mounted on the floating link 150 with the jockeypulley 31 positioned at an eccentric pivot 184, which is eccentric tothe jockey pulley 31 pivot. This eccentricity affects the motion of thejockey pulley throughout the travel of the derailleur. With the linearmotion mechanism 110, an eccentrically mounted cage assembly 30 moves ina rectilinear path at the eccentric mount 184. Pivoting about theeccentric mount 184 allows an alternate relative movement between thejockey pulley 31 and the idler pulley 32, allowing for greaterflexibility in tuning the derailleur to the application. Adjusting thelinear distance L between the jockey pulley pivot 182 and the eccentricpivot 184 adjusts the relative rotation of the jockey pulley 31 relativeto the eccentric pivot 184 and the relative rotation of the idler pulley32 relative to the eccentric pivot 184.

In accordance with one embodiment, the pivotal attachment between thecage 30 and the floating link 150 (e.g. either concentrically oreccentrically) can be oriented so that the jockey 31 and idler pulley 32axes are not parallel to the wheel axis indicated by Z. This orientationcan be relative to yaw, roll or pitch. As a result, the angles Al of thederailleur pulley 31, 32 axes relative to the wheel axis Z remainconstant throughout the entire travel range of the mechanism. Dependingon the cassette 6 and chain ring configuration, adjustment of the anglesof the derailleur pulleys 31, 32 relative to the wheel axis may optimizeshifting performance by maximizing efficiency of the chain/belt 5 andcassette 6 engagement and may minimize wear from dropped chains/belts 5.Accordingly, in various embodiments and referring to FIGS. 5E-F, thejockey and idler pulley axes 182, 184 are not parallel to the wheel axisin roll. For example, the angle between the jockey and idler pulley axes182, 184 and the wheel axes Z is greater than 1 degree. In a moreparticular example, the angle between the jockey and idler pulley axes182, 184 and the wheel axes Z is from 1 to 5 degrees. In a still moreparticular example, the angle is about 2 degrees.

In accordance with one embodiment, the pivotal attachment between thecage 30 and the floating link 150 (e.g. either concentrically oreccentrically) can be oriented so that the jockey 31 and idler pulley 32axes are substantially parallel to the wheel axis indicated by Z.Depending on the cassette and chain ring configuration, this mayoptimize shifting performance by maximizing efficiency of the chainTheltsprocket system and may minimize chain wear from dropped chains/belts.As an example and again referring to FIGS. 5E and 5F, the jockey andidler pulley axes 182, 184 are substantially parallel to the wheel axis.Stated another way, the angle between the pulley axes 182, 184 and thewheel axis Z is approximately zero.

As noted previously, an actuation force may cause movement in thederailleur linkage in either an electro-mechanical or mechanical controlsystem; there is an actuation ratio between the actuation force inputand derailleur output that dictates the amount of relative motion thederailleur moves as the shifter is actuated. There is a ratio betweenthe amount of actuator movement (e.g. cable pull, piston/linear servothrow, or radial servo rotation) to the amount of lateral movement(movement in the direction of the wheel axis to force the chain to shiftcogs) of the derailleur. With a typical parallelogram design, themechanism's linkage path is dependent upon the link lengths and axesgeometry. In order to achieve an optimum linkage path and actuationratio in a parallelogram mechanism, it is common to add additionalcomplex features such as pulley wheels and extended links. These itemsadd weight and complexity.

With the disclosed structure and mechanism, the lengths of theindividual links of linkset 145 a and linkset 145 b can varyindependently of the linear path of the mechanism. Therefore, theactuation ratio of the mechanism can be tuned independent of themechanism's linear path. For example, FIG. 14 illustrates one particularexample of an actuation ratio using a mechanical cable on a linearderailleur. As shown, the y axis of the table indicates the distance inmm that the linear derailleur moves and the x axis indicates thecorresponding distance of cable pull to achieve the derailleur movement.

FIGS. 10-14 are graphical representations of tests or models based onthe linear derailleurs discussed herein compared to two differentparallelogram designs provided by separate companies. In each comparisonthe derailleur SRAM XX1 is provided by Company 1 and the derailleurShimano Rdm9000 is provided by Company 2. FIGS. 10 and 12 are a graphsthat shows an example model of the yaw and roll and angle deviation ofthe derailleur pulley axes for two example parallelogram linkagederailleurs compared to that of the disclosed structure using arectilinear linkage. Note that in FIG. 10, the pulley axes of therectilinear linkage derailleur are parallel to the wheel axis throughoutthe entire travel range in this particular case in both roll and yaw.Both of the parallelogram designs deviate from zero in both roll andyaw. In FIG. 12 the pulley axes of the rectilinear linkage derailleurare set at an angle with the yaw at about −1.5 degrees and the roll atabout −0.9 degrees. Still, the linear derailleur remains constantthrough the range of travel.

FIGS. 11 and 13 are graphs that shows the pitch angle deviation of thederailleur pulley axes for parallelogram linkage of Company 2 andCompany 1 compared to that of the disclosed structure which uses alinear derailleur linkage as discussed herein. Note that in FIG. 11, thepulley axes of linear derailleur are parallel to the wheel axisthroughout the entire travel range throughout the entire travel range inpitch. However both of the parallelogram designs deviate from zero inpitch but Company 1 does remain constant in pitch unlike Company 2. Alsoin FIG. 13 with the pitch set at about 90 degrees, the pulley axes oflinear derailleur remain constant relative to their initial pitch.

In accordance with various embodiments, as illustrated in FIGS. 8, 9Aand 9B, the derailleur receives an actuation force that can becontrolled mechanically or electro-mechanically via a known shiftermechanism or electro-mechanical mechanism typically located on or nearthe handlebars. The actuation force applied can be applied through butis not limited to a mechanical cable (see e.g. FIG. 3A actuator 170),linear/radial electro-mechanical servo (see e.g. FIG. 9A and 9B actuator370) or a hydraulic/pneumatic cylinder (see e.g. FIG. 8 actuator 270).In the electro-mechanical control case, the applied actuation force iscontrolled by an electro-mechanical shifter which is connected to amicro-processor and battery to logically control the desired actuationforce and therefore derailleur output motion. In the mechanical controlcase, the applied actuation force is controlled by a mechanical shifterto mechanically control the desired actuation force and thereforederailleur output motion. Derailleurs are positioned on the bike framenear the front, rear, or both gear cassettes. In embodiments having arotary servo 370, the servo 370 drives one of the non-stationary links150 about one of its axes of rotation. There is a ratio between theamount of actuator movement (e.g. cable pull, piston motion, or servorotation/translation) to the amount of the mechanism's lateral movement(movement in the direction of the wheel axis). Utilizing a linearderailleur helps to improve this ration providing greater control to thebicycle user.

The spatial linkage derailleur hanger constrains the floating link to arectilinear motion. The relationship between the pulley wheel axes andthe wheel axis is operably adjusted for tuning the derailleurperformance. The disclosed structure allows the angle of the pulleywheel axes to remain constant throughout the full motion of themechanism. In various embodiments, the pulley wheel axes may remainparallel to the wheel axis throughout full motion of the mechanism. Inother embodiments, the pulley wheel axes may be skewed relative to thewheel axis. The specific motion of the spatial linkage derailleur allowsthe derailleur to be optimized for efficiency (e.g. less belt or chainwear, improved efficiency, etc.), shifting quality and minimal chancesof chain derailment. Also, since the linear motion is independent of thefloating link lengths and there is a large amount of freedom for theplacement of the floating link axes on both the fixed and floating link.This allows the mechanism to be easily controlled due to flexibility indesigning the actuation ratio. In addition the structure lends itself tomultiple configurations with a small envelop. This provides moreflexibility in bike frame design as well as minimizes the chances ofhitting the derailleur on obstacles while riding.

Having described several embodiments herein, it will be recognized bythose skilled in the art that various modifications, alternativeconstructions, and equivalents may be used. The various examples andembodiments may be employed separately or they may be mixed and matchedin combination to form any iteration of the alternatives. Additionally,a number of well-known processes and elements have not been described inorder to avoid unnecessarily obscuring the focus of the presentdisclosure. Accordingly, the above description should not be taken aslimiting the scope of the invention. Those skilled in the art willappreciate that the presently disclosed embodiments teach by way ofexample and not by limitation. Therefore, the matter contained in theabove description or shown in the accompanying drawings should beinterpreted as illustrative and not in a limiting sense. For example,while the various figures shown herein are shown with rear derailleurs,the various concepts are equally applicable to front derailleurs. Insuch an embodiment, the stationary link may be mounted to a bracket, theseat tube, the crank housing or the like, with the floating linkmounting to a chain guide. The floating link and the chain guide maymove in a substantially rectilinear path aligning the chain with thefront chain rings.

Any and all references specifically identified in the specification ofthe present application are expressly incorporated herein in theirentirety by reference thereto. The term “about,” as used herein, shouldgenerally be understood to refer to both the corresponding number and arange of numbers. Moreover, all numerical ranges herein should beunderstood to include each whole integer within the range.

The following claims are intended to cover all generic and specificfeatures described herein, as well as all statements of the scope of thepresent method and system, which, as a matter of language, might be saidto fall there between.

We claim:
 1. A bicycle comprising: a frame having a gear cassettemounted thereon, the gear cassette having an axis of rotation; a drivemember engaging the gear cassette; a derailleur positioned on the frameadjacent the gear cassette, with the derailleur having a cage assemblywith two pulleys each defining an axis of rotation and the drive memberengaging each of the pulleys, wherein the derailleur also includes aspatial linkage having: a stationary link and a floating link whereinthe path of the floating link is substantially linear throughsubstantially its entire range of motion.
 2. The bicycle of claim 1,wherein the gear cassette is a rear gear cassette operably associatedwith a rear wheel.
 3. The bicycle of claim 1, wherein the gear cassetteis a front chain ring set operably associated with a crank.
 4. Thebicycle of claim 1, wherein the pulley axes of the cage assembly isparallel to the axis of rotation of the gear cassette and remainsparallel to the axis of rotation of the gear cassette throughout itsentire range of motion.
 5. The bicycle of claim 1, wherein the pulleyaxes of the cage assembly is not parallel to the axis of rotation of thegear cassette and remains not parallel to the axis of rotation of thegear cassette throughout its entire range of motion.
 6. The bicycle ofclaim 1, wherein the spatial link is an over-constrained spatial 6Rlinkage.
 7. The bicycle of claims 1, wherein the statonary link isattached to the bicycle frame.
 8. The bicycle of claim 1, wherein thecage assembly is pivotally connected concentrically on the floatinglink.
 9. The bicycle of claim 1, wherein the cage assembly is pivotallyconnected eccentrically on the floating link.
 10. The bicycle of claim1, wherein an actuation force is applied to the derailleur to causemotion from a first position to a second position, and at least onereturn mechanism is utilized to urge the derailleur from the secondposition towards the first position.
 11. The bicycle of claim 10,wherein the actuation force may be a mechanically, electrically, orhydraulically driven.
 12. The bicycle of claim 11, wherein the returnmechanism may include at least one spring selected from one of the groupof a torsion spring, and/or an extension spring.
 13. The bicycle ofclaim 11, wherein input activation of the linkage is via a mechanicalcable.
 14. The bicycle of claim 11, wherein input activation of thelinkage is via an electronic servo.
 15. The bicycle of claim 11, whereinthe input activation of the linkage is via a plunger.
 16. A derailleurfor a bicycle comprising: a stationary link and a floating link whereinthe path of the floating link is substantially linear throughsubstantially all of the floating link's range of motion, wherein thefloating link is operable to move a drive member which is operable toengage a gear cassette, wherein the stationary link is operable to bepositioned on a frame having the gear cassette mounted thereon, the gearcassette having an axis of rotation, wherein the stationary link ispositioned on the frame adjacent the gear cassette.
 17. A derailleur ofclaim 16, wherein the gear cassette is a rear gear cassette operablyassociated with a rear wheel.
 18. A derailleur of claim 16, wherein thegear cassette is a front gear cassette operably associated with a crank.19. The derailleur of claim 16, wherein the pulley axes of the cageassembly remain parallel to the axis of rotation of the gear cassettethroughout its entire range of motion.
 20. The derailleur of claim 16,wherein the spatial link is an over-constrained spatial 6R linkage. 21.The derailleur of claim 16, wherein the stationary link is connected tothe bicycle frame.
 22. The derailleur of claim 16, wherein the cageassembly is pivotally connected concentrically on the floating link. 23.The derailleur of claim 16, wherein the cage assembly is pivotallyconnected eccentrically on the floating link.
 24. The derailleur ofclaim 16, wherein an actuation force is applied to the derailleur tocause motion from a first position to a second position, and at leastone return mechanism is utilized to urge the derailleur from the secondposition towards the first position.
 25. The derailleur of claim 24,wherein the actuation force is a mechanically, electrically, orhydraulically driven.
 26. The derailleur of claim 24, wherein the returnmechanism includes at least one spring selected from one of the group ofa torsion spring, and/or an extension spring.
 27. The derailleur ofclaim 25, wherein input activation of the linkage is via a mechanicalcable.
 28. The derailleur of claim 25, wherein input activation of thelinkage is via an electronic servo.
 29. The derailleur of claim 25,wherein the input activation of the linkage is via a piston.
 30. Abicycle comprising: a frame having a gear cassette mounted thereon, thegear cassette having an axis of rotation; a drive member engaging thegear cassette; a derailleur positioned on the frame adjacent the gearcassette, with the derailleur having a stationary link and a floatinglink, wherein the stationary link is connected to the floating link viaa fist linkset and a second linkset, each linkset having a plurality ofaxis of rotation, wherein the axes of rotation in the first link set arenot parallel to the axes of ration in the second linkset.